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BGA X-ray Inspection- a How To

About: I am principal of BEST Inc. Had 18+ years in running small businesses. By trade I am an electrical engineer and holds patents in various fields including industrial controls, surface science and PCB rework/r...
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This Instructable will teach you how to prepare use and 2D x-ray system to inspect a BGA , as well as some hints on what to look for when performing BGA x-ray inspection You will need:

X-ray system capable of holding the PCB

PCB

ESD smock

ESD wrist strap

Proper ESD footwear .

Step 1: Review

Review the inspection criteria of the contracting customer. IPC-A-610 inspection criteria for the given class of the assembly is one of the default guidelines. Also look at IPC-7095 to derive your own acceptance criteria for x-ray inspection of BGAs.

Step 2: Removal of PCB

Remove PCB from static shielding bag. Make sure that you are properly grounded when handling an electronicassembly according to EOS/ESD 2020 guidelines or internal company guidelines..

Step 3: Marking

Identify the area of interest and mark with a rework label on the area or device of interest. Thie will help in locating the source..

Step 4: Loading the BGA Into the X-ray Chamber

Load the PCB into the x-ray chamber. Make sure all of the necessary precautions are taken before operating an X-ray machine. Initiate the x-ray. Make sure there is a high enough contrast in your image so that all voids and opens are in sight.

Using the laser pointer in the x-ray system, manipulate the table such that the area of interest shows up on the operator interface x-ray screen.

Step 5: Organization of the Digital BGA X-ray Files

You will most likely take many images of the BGA from various angles, so make sure a folder for both images and video taken are set up before shooting. Place the images in the correct folder for archiving with the job.

Step 6: Inspecting the BGA X-ray Images

Locate the BGA requiring x-ray inspection. Inspect looking for faults such as shorts, opens, bridges and the like. Take snapshots or videos of these anomalies

Inspect the entire BGA then zoom in to "walk" around the area array device. Pay notice to ball shape consistency, solder sphericity, solder shorts, solder balls and other anomalies.

Zoom in to exam the consistency of ball sizes, concentricity of the balls, voiding and other issues. Analyze the part solder ball images of the BGA in a set pattern to make sure you cover all of the balls.

Step 7: Wrap-Up

When BGA x-ray inspection is complete, remove the PCB from the x-ray chamber. Remove the rework label , then place back into static shielding bag.